1. Field of the Invention
The present invention relates to an electronic musical instrument with an automatic musical accompaniment playing system for automatically playing musical accompaniment chords such as rhythmic chords and melodic chords (arpeggios).
2. Prior Art
There has been proposed an electronic musical instrument which includes an automatic musical accompaniment playing system for automatically playing musical accompaniment chords such as rhythmic chords and melodic chords (arpeggios) in accordance with chords determined by keys depressed on an associated keyboard. Each rhythmic chord is played by intermittently generating all constituent tones of the chord at timings determined by a selected rhythm, and each melodic chord is played by selectively generating one or more constituent tones of the chord in an order determined by a selected rhythm. Such conventional electronic musical instrument generally comprises, in addition to tone generating channels for generating principal tones, a plurality of tone generating channels for exclusive use by the automatic musical accompaniment system. Thus, the conventional electronic musical instrument has needed a relatively large number of tone generating channels. Moreover, the tone generating channels for the exclusive use operate only when the automatic musical accompaniment system is used and are all idle in other cases.
U.S. Pat. No. 4,365,532 issued on Dec. 18, 1982 and U.S. Pat. No. 4,450,745 issued on May 29, 1984 disclose an electronic musical instrument in which tone generating channels are selectively assigned to upper keyboard tones or manual performance tones and to lower keyboard tones or automatic performance tones. The assignment mode of the channels is changed according to the performance mode of the instrument. However, in this instrument, the tone generating channels to be assigned to lower keyboard tones or automatic performance tones are predetermined. For example, if there are ten tone generating channels, channels 1 to 5 are always assigned to the automatic performance tones when an automatic performance mode is selected. This change of assignment is made irrespective of the conditions of the channels 1 to 5. Therefore, generating tone or tones may be cut if the automatic performance mode is selected when any of the channels 1 to 5 is being used for tone generation.